4K has four times the amount of pixels than the current digital standard. Most cinemas now use digital systems instead of actual film, and those are in 2K. 4K has slightly more information in each picture than an IMAX movie. These digital standards are more important now, because Fujifilm is no longer making film for movies, leaving Kodak, which is restructuring after declaring bankruptcy, the sole provider of 35mm film.

Earlier this summer, the film center showed their first 4K film, Raiders of the Lost Ark. In another theater, they were showing the film in 2K. To compare the difference, Marty Rubin, the associate director of programming, ran back and forth between the two theatres.

He noticed two:

In the scene where Indiana Jones is giving a lecture, you can read the writing on his notes if you watch the movie in 4K.

When Marion Ravenwood, played by Karen Allen, plays her drinking game, you can vividly see the bottles at the back of the bar when watching in 4K.

“There is a difference and it can be quantified by so many pixels,” Rubin says. “A rough analogy between 4K and 2K would sort of be the difference between Blu-ray and DVD.”

Mark Schubin, a technology consultant for the film and TV industries, disagrees. He says ordinary viewers can tell the difference between Blu-ray and DVD from their TV, but the difference between 2K and 4K isn’t as obvious.

“The one place where you will notice it is when you’re buying a TV because you tend to stand closer to a screen when you buy a set than when you watch it at home,” he says.

To really see the difference between 2K and 4K, you need an exceptionally large screen (more than 60 inches diagonal for TV or IMAX-sized for theatres) or you have to be sitting very close to the screen, says Kenneth Willliams, executive director of an entertainment technology think tank at the University of Southern California’s (USC) School of Cinematic Arts.

If you look at a tablet from across a living room, you wouldn’t see any of the details, explains Spencer Stephens, chief technology officer at Sony. If you have your nose pressed to the screen, you can see the individual pixels so it wouldn’t look good. Somewhere between those distances is a sweet spot. Back in the days of black and white film, audiences would sit in a long thin rectangular theatre far away from the screen, because that’s where they could see the detail without pixilation. Now as movies are shown in full color on large screens, cinemas have stadium seating. As screens get bigger and/or audiences get closer, more of the details will be clear with a 4K projection.

However, even if a movie is shot in 4K and shown at 4K, it may have been downsized during production, says Michael Fink, an Oscar-nominated visual effects supervisor who worked on movies like Avatar and Tree of Life, and also teaches at the University of Southern California’s School of Cinematic Arts.

He says that most production equipment for color-correction and other effects don’t work in 4K, so the crew will convert the files to 2K, and change it back to 4K afterwards.

He also says that the resolution doesn’t matter as much to him, as the frame rate. The frame rate is the speed at which the images are shown to make it seem as if something is moving on the screen. Most movies are shown in 24 frames per second (fps), and the first Hobbit movie generated quite a discussion with its 48 fps screenings. Fink says that in a 60 fps movie, audiences will be able to see performances more clearly, and it’ll be better than 48 fps.

“In an action scene, when the hero swings the sword, you’ll know it’s the hero. It can’t be the stunt double hiding in a motion blur and so it had better be the hero or be really high quality face replacement,” Fink says. “You’ll see that performance, so a lot more is going to be demanded of actors.”

All in all, Fink reckons the frame rate matters more than the number of pixels in terms of image quality.

That’s not a problem because 4K wasn’t meant to be a huge shift, says Kenneth Williams of USC.

He was part of the Digital Cinema Initiatives, a joint venture of the large studios including Disney, Universal and Warner Brothers. The group was created in 2002, and together they created standards for digital film with two categories: 2K and 4K, he says.